Madrid Barajas Layover on Way to Porto

Hi, Friends. I'm getting ready to walk the Portuguese Coastal Camino from Porto around September 20. (Just finished Central from Valenca to Santiago in July and can't get enough). Does anyone have experience or knowledge about the layover procedures at the Barajas Aeropuerto? I've read suggestions to take the train to the city, but I wonder about time exiting and reentering. Even though I have one ticket from American, the connection is on Iberia and I haven't found information about the connections. I will be flying from NYC to Porto on September 15, arriving next day at 8:30 a.m. with a 7 hour layover in Madrid and flight to Porto scheduled to depart Madrid at 3:30 p.m. Any ideas? Catching up on sleep would be my preference, but not too practical, so now it's Plan B. Thank you for any suggestions. I love all the route recommendations and stories about the Portuguese on the Forum. Can't wait to begin! Again! Irene

Thanks so much for your reply, Jill. I bet trying to return in time with a five hour layover would be a stretch. And I'm definitely concerned even with seven hours, especially when I don't know what the exit and return procedures will be. A lot is unknown about that time in between. There must be some security checks, but would we exit after the general Spain entry process is completed, which could take a long time. I've flown in and out of Barajas several times, but have never connected! If I don't go into the city, I hope I'll make a few new friends by the Cafe and find a great book in between naps. Buen Camino to you. Irene